Improving Fault Isolation Using Iterative Diagnosis

Author(s):  
Kevin Gearhardt ◽  
Chris Schuermyer ◽  
Ruifeng Guo

Abstract This paper presents an iterative diagnosis test generation framework to improve logic fault diagnosis resolution. Industrial examples are presented in this paper on how additional targeted pattern generation can be used to improve defect localization before physical failure analysis of a die. This enables failure analysts to be more effective by reducing the dependence on the more expensive physical fault isolation techniques.

Author(s):  
Haonan Bai ◽  
Lan Yin Lee ◽  
Yang Jing ◽  
Peter Floyd Salinas ◽  
Kok Keng Chua

Abstract Failure analysis and defect localization on 28nm All Programmable Zynq System-on-Chip (SoC) device is extremely challenging. While conventional FPGA, which only consists of the Programmable Logic, has greater ease and flexibility in pattern generation during fault isolation, the all programmable SoC device integrates a dual ARM Cortex-A9 cores with Programmable Logic (PL) in a single chip. The cache data access in-between processor and PL is more complex and test methodology has lesser degree of control on cache data flow and stack sequence. This paper introduced an advanced fault isolation test methodology combining Software Development Kit (SDK) with scan based diagnostic test for cache failures. It successfully pinpoint to failure locations with physical defects found. As conventional physical failure analysis approaches using SEM based passive voltage contrast could not observe any abnormalities, current imaging and nano-probing measurement using AFP played critical roles in detecting nano-ampere leakages prior subsequent TEM analysis. The findings were then feedback to the foundry for process improvement. Furthermore, a new screening methodology is innovated where an extreme low-voltage test at high temperature in Automatic Test to detect and eliminate the process marginal leakage failure.


Author(s):  
Chris Eddleman ◽  
Nagesh Tamarapalli ◽  
Wu-Tung Cheng

Abstract Yield analysis of sub-micron devices is an ever-increasing challenge. The difficulty is compounded by the lack of in-line inspection data as many companies adopt foundry or fab-less models for acquiring wafers. In this scenario, failure analysis is increasingly critical to help drive yields. Failure analysis is a process of fault isolation, or a method of isolating failures as precisely as possible followed by identification of a physical defect. As the number of transistors and metal layers increase, traditional fault isolation techniques are less successful at isolating a cause of failures. Costs are increasing due to the amount of time needed to locate the physical defect. One solution to the yield analysis problem is scan diagnosis based fault isolation. Previous scan diagnosis based techniques were limited with little information about the type of fault and confidence of diagnosis. With new scan diagnosis algorithms it is now possible to not only isolate, but to identify the type of fault as well as assigning a confidence ranking prior to any destructive analysis. This paper presents multiple case studies illustrating the application of scan diagnosis as an effective means to achieve yield enhancement. The advanced scan diagnostic tool used in this study provides information about the fault type as well as fault location. This information focuses failure analysis efforts toward a suspected defect, decreasing the cycle time required to determine root cause, as well as increasing the over all success rate.


Author(s):  
C.C. Ooi ◽  
K.H. Siek ◽  
K.S. Sim

Abstract Focused ion beam system has been widely used as a critical failure analysis tool as microprocessor technology advances at a ramping speed. It has become an essential step in failure analysis to reveal physical defects post electrical fault isolation. In this highly competitive and challenging environment prevalent today, failure analysis throughput time is of utmost important. Therefore quick, efficient and reliable physical failure analysis technique is needed to avoid potential issues from becoming bigger. This paper will discuss the applications of FIB as a defect localization and root cause determination tool through the passive charge contrast technique and pattern FIB analysis.


Author(s):  
S.H. Goh ◽  
B.L. Yeoh ◽  
G.F. You ◽  
W.H. Hung ◽  
Jeffrey Lam ◽  
...  

Abstract Backside frequency mapping on modulating active in transistors is well established for defect localization on broken scan chains. Recent experiments have proven the existence of frequency signals from passive structures modulations. In this paper, we demonstrate the effectiveness of this technique on a 65 nm technology node device failure. A resistive leaky path leading to a functional failure which, otherwise cannot be isolated using dynamic emission microscopy, is localized in this work to guide follow on failure analysis.


Author(s):  
Tommaso Melis ◽  
Emmanuel Simeu ◽  
Etienne Auvray

Abstract Getting accurate fault isolation during failure analysis is mandatory for success of Physical Failure Analysis (PFA) in critical applications. Unfortunately, achieving such accuracy is becoming more and more difficult with today’s diagnosis tools and actual process node such as BCD9 and FinFET 7 nm, compromising the success of subsequent PFA done on defective SoCs. Electrical simulation is used to reproduce emission microscopy, in our previous work and, in this paper, we demonstrate the possibility of using fault simulation tools with the results of electrical test and fault isolation techniques to provide diagnosis with accurate candidates for physical analysis. The experimental results of the presented flow, from several cases of application, show the validity of this approach.


Author(s):  
Seth J. Prejean ◽  
Joseph Shannon

Abstract This paper describes improvements in backside deprocessing of CMOS (Complimentary Metal Oxide Semiconductor) SOI (Silicon On Insulator) integrated circuits. The deprocessing techniques described here have been adapted from a previous research publication on backside deprocessing of bulk CMOS integrated circuits [1]. The focus of these improvements was to provide a repeatable and reliable methodology of deprocessing CMOS devices from the backside. We describe a repeatable and efficient technique to deprocess flip chip packaged devices and unpackaged die from the backside. While this technique has been demonstrated on SOI and bulk devices, this paper will focus on the latest SOI technology. The technique is useful for quick and easy access to the transistor level while preserving the metal interconnects for further analysis. It is also useful for deprocessing already thinned or polished die without removing them from the package. Removing a thin die from a package is very difficult and could potentially damage the device. This is especially beneficial when performing physical failure analysis of samples that have been back thinned for the purpose of fault isolation and defect localization techniques such as: LIVA (Laser Induced Voltage Alteration), TIVA (Thermally Induce Voltage Alteration), SDL [2] (Soft Defect Localization), and TRE (Time Resolved Emission) analysis. An important fundamental advantage of deprocessing SOI devices is that the BOX (Buried Oxide) layer acts as a chemical etch stop when etching the backside or bulk silicon. This leaves the transistor active silicon intact for analysis. Further delayering allows for the inspection of the active silicon, gate oxide, silicide, spacers, and poly. After deprocessing the transistor level, the metal layers are still intact and, in most cases, still electrically connected to the outside world. This can provide additional failure analysis opportunities.


Author(s):  
Hui Peng Ng ◽  
Angela Teo ◽  
Ghim Boon Ang ◽  
Alfred Quah ◽  
N. Dayanand ◽  
...  

Abstract This paper discussed on how the importance of failure analysis to identify the root cause and mechanism that resulted in the MEMS failure. The defect seen was either directly on the MEMS caps or the CMOS integrated chip in wafer fabrication. Two case studies were highlighted in the discussion to demonstrate how the FA procedures that the analysts had adopted in order to narrow down to the defect site successfully on MEMS cap as well as on CMOS chip on MEMS package units. Besides the use of electrical fault isolation tool/technique such as TIVA for defect localization, a new physical deprocessing approach based on the cutting method was performed on the MEMS package unit in order to separate the MEMS from the Si Cap. This approach would definitely help to prevent the introduction of particles and artifacts during the PFA that could mislead the FA analyst into wrong data interpretation. Other FA tool such as SEM inspection to observe the physical defect and Auger analysis to identify the elements in the defect during the course of analysis were also documented in this paper.


Author(s):  
Philippe Perdu ◽  
Romain Desplats

Abstract IDDQ testing detects a majority of faults in logic ICs. To improve defect coverage with very short test patterns, IDDQ testing has been integrated in fault simulators embedded with automatic test pattern generation (ATPG) algorithms. Nevertheless, for failure analysis purposes, this progress has not eliminated the complex task of fault isolation at the silicon level of ICs. Defect localization is facilitated with IDDQ testing because the defect is detected as soon as it is activated inside the device. At the failed vector, abnormal IDDQ current is measured and accurate localization of the corresponding defect inside the chip can be performed. Thermally related techniques or emission microscopy can be used for this localization process. Very powerful tools like electron beam testers can also be used to deeply analyze faulty devices by internal contactless testing. In this paper, we will present an application of IDDQ testing for fault detection and some key issues regarding localization of the corresponding defect: • Appropriate techniques, • Switching from electrical testing to fault localization, • Modifying the test pattern to shorten the localization process, • Constructing a localization method based on an IDDQ diagnostic.


Author(s):  
Srikanth Venkataraman ◽  
Scott B. Drummonds

Abstract Logic fault diagnosis or fault isolation is the process of analyzing failing random logic portions of a chip to isolate the cause of failure. Fault diagnosis or fault isolation (FI) plays an important role in multiple applications at different stages of design and manufacturing. Most currently deployed FI techniques for random logic fault isolation include physical techniques with limited automated diagnosis followed by e-beam and/or laser voltage probing (LVP) on packaged parts. This paper will present the methodology and FI results obtained by executing automated scan based diagnosis on a chipset product (440BX). The logic diagnosis techniques used are presented along with simulation and Failure Analysis (FA) results


Author(s):  
Dat T. Nguyen ◽  
Frank Huang

Abstract Poly/metal stacked capacitors present challenges in terms of capacitor access and defect localization. As for defect localization, liquid crystal or thermal localization (also OBIRCH/TIVA) and passive voltage contrast (PVC) are used. PVC was found to be effective in terms of finding the bad stacked capacitor and a bad capacitor within the stack. This paper highlights brief process steps in 3-layer polysilicon/metal stacked capacitors. It discusses FA on stacked capacitors, providing information on fault isolation and capacitor access. It presents a case study on differentiating defective capacitors which failing due to vertical shorting. Internal probing between the capacitors within a stack allowed the differentiation between capacitor leakage and capacitor-capacitor shorting. For capacitor leakage, the defect can be identified by parallel lapping to remove the upper capacitor plate. For capacitor-capacitor short, if there is no visual defect seen, Pt chemical etch can be applied for PVC inspection.


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